“To scrub, or not to scrub” is a question that I get asked quite frequently in this job. It’s certainly a contentious issue at the moment with plenty of fierce debate centred on the long-term impact of these specialised exhaust gas cleaning systems.

To answer honestly, both myself and ‘the jury’ are still very much out on the long-term viability of scrubbers, from a financial, environmental and, ultimately, political standpoint.

I do not dispute that the deployment of exhaust gas cleaning systems can potentially result in significant savings in operational costs, particularly for very large ships calling at major ports, as users can scrub lower-priced high sulphur fuel oils rather than buy more expensive distillates or very low sulphur fuel oils.

But this assumes a readily-available supply of high sulphur fuel and a substantial discount versus low sulphur fuels. Despite numerous industry forecasts and consultants’ predictions, neither of these is 100 per cent guaranteed, especially in smaller, less flexible ports. This applies to all scrubber systems, whether open loop, closed loop or hybrid.

It is perfectly clear that the technology does work – although if it does break down at any point, the shipowner may be open to regulatory problems as well as mechanical ones, which is something to be aware of when investing in vessels once the IMO 2020 regulation comes into force.

Overall, my biggest concerns are environmental and political. Already, open loop scrubbers are increasingly being labelled as environmentally damaging because they remove sulphur emissions from the air only to discharge them into the sea.

Although it would be ‘nice’ to think that scrubbers provided a quick fix for the sulphur cap, enabling companies to book in and out of a retrofit for business as usual, the disposal of the washwater and the potentially costly maintenance of the scrubber doesn’t paint an entirely reliable picture of the future.

A number of ports around the world have either already banned or are about to ban their use in port (including Antwerp, Singapore and Fujairah) or are considering what their stance should be (including Gibraltar). And, the European Union Water Framework Directive is also looking to restrict the use of open loop scrubbers if water quality starts to fall below agreed levels.

Indeed, last year independent shipping analyst Ned Molloy, told The Guardian that although the scrubbers permissible as a method in which to meet IMO 2020 regulations, they were little more than an “environmental dodge”.

Closed loop and hybrid scrubbers are not yet under that particular microscope, but once attention turns from sulphur emissions to carbon emissions (which scrubber systems do not reduce), they too will be scrutinised.

Once the environmental lobby really sinks its teeth into the use of scrubbers – as it is already just starting to do – politicians will not be far behind.

Therefore, regardless of their effectiveness, I foresee a time when political imperatives driven by environmental lobbying may put an end to the use of scrubbers.

Additionally, if a larger number of ports ban open loop scrubbers, forcing users to use closed loop or hybrid varieties, all ships using scrubbers will be obliged to retain the scrubber effluent on board until a suitable waste disposal site can be found. This might easily end up being both expensive and not necessarily located at the scheduled ports of call for a vessel that needs to discharge. While waiting to offload scrubber discharge, a ship will also have to carry the extra load, thereby reducing its bunker or cargo carrying capacity, hence costing money.

Whilst the shipping industry might once have hoped that ‘sulphur scrubbers’ might provide a straightforward solution to IMO 2020 compliance, I rather suspect that might be wishful thinking to think that’s a problem solved.

If I were a bunker buyer, I would be cautious in adopting scrubbing technology based on the current state of affairs, chiefly because once the issue of sulphur has been addressed, environmental and political attention will shift quickly to carbon, for which scrubbers have no answer.